\\[-1.8ex] Soil Heterogeneity & $-$4.560$^{***}$ & $-$5.541$^{***}$ & $-$4.164$^{***}$ & $-$2.994$^{***}$ & $-$2.380$^{***}$ & $-$2.206$^{***}$ \\ 
  & (1.343) & (0.891) & (0.796) & (0.800) & (0.629) & (0.602) \\ 
\\[-1.8ex] 
Oster $\delta$ for $\beta=0$ &  & -156.86 & 5.25 & 2.76 & 1.99 & 1.78 \\ 
Observations & 23,437 & 23,437 & 23,437 & 23,437 & 23,437 & 23,375 \\ 
R$^{2}$ & 0.006 & 0.469 & 0.513 & 0.548 & 0.566 & 0.573 \\ 
